The invention relates generally to probe and sensor systems, and more particularly to a probe for measuring a clearance between two objects.
Various types of probe and sensor systems have been used to measure the distance between two objects. In addition, the probe systems have been used in various applications. For example, a turbine has a number of turbine blades that are disposed adjacent to a shroud. The clearance between a turbine blade and the shroud varies depending on the temperature of the turbine blade. For example, the clearance between the shroud and the turbine blade is greatest when the turbine is cold and gradually decreases as the turbine heats up. It is desirable that a gap or clearance between the turbine blade and the shroud be maintained for safe and effective operation of the turbine. A sensor may be disposed within the turbine to measure the distance between the turbine blades and the shroud. The distance may be used to direct movement of the shroud to maintain the desired displacement between the shroud and the turbine blades.
Efficiency of rotating components such as turbines and compressors are also strongly affected by a gap or clearance between a rotating blade and a component casing. In general, minimizing the gap maximizes the efficiency of the components. However, a small amount of clearance is desirable to prevent the rotating blade from hitting the component casing. In certain applications, a capacitance probe is employed to measure the distance between two objects. The probe is located on one of the objects and measures a capacitance with respect to the other object for estimating the clearance between the two objects. However, for high temperature applications, such as gas turbines, existing devices are expensive and difficult to manufacture, due to the strict requirements necessary for the devices to operate in harsh operating environments.
Therefore, there is a need for an improved sensor system to address the aforementioned issues.